/*
   BLAKE2 reference source code package - reference C implementations

   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
   your option.  The terms of these licenses can be found at:

   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
   - OpenSSL license   : https://www.openssl.org/source/license.html
   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0

   More information about the BLAKE2 hash function can be found at
   https://blake2.net.
*/

#include <stdint.h>
#include <string.h>
#include <stdio.h>

#include "blake2.h"

#define BLAKE2_INLINE

static BLAKE2_INLINE uint32_t load32( const void *src )
{
  uint32_t w;
  memcpy(&w, src, sizeof w);
  return w;
}

static BLAKE2_INLINE void store16( void *dst, uint16_t w )
{
  memcpy(dst, &w, sizeof w);
}

static BLAKE2_INLINE void store32( void *dst, uint32_t w )
{
  memcpy(dst, &w, sizeof w);
}

static BLAKE2_INLINE uint32_t rotr32( const uint32_t w, const unsigned c )
{
  return ( w >> c ) | ( w << ( 32 - c ) );
}

/* prevents compiler optimizing out memset() */
static BLAKE2_INLINE void secure_zero_memory(void *v, size_t n)
{
  static void *(*const volatile memset_v)(void *, int, size_t) = &memset;
  memset_v(v, 0, n);
}

static const uint32_t blake2s_IV[8] =
{
  0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL,
  0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL
};

static const uint8_t blake2s_sigma[10][16] =
{
  {  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15 } ,
  { 14, 10,  4,  8,  9, 15, 13,  6,  1, 12,  0,  2, 11,  7,  5,  3 } ,
  { 11,  8, 12,  0,  5,  2, 15, 13, 10, 14,  3,  6,  7,  1,  9,  4 } ,
  {  7,  9,  3,  1, 13, 12, 11, 14,  2,  6,  5, 10,  4,  0, 15,  8 } ,
  {  9,  0,  5,  7,  2,  4, 10, 15, 14,  1, 11, 12,  6,  8,  3, 13 } ,
  {  2, 12,  6, 10,  0, 11,  8,  3,  4, 13,  7,  5, 15, 14,  1,  9 } ,
  { 12,  5,  1, 15, 14, 13,  4, 10,  0,  7,  6,  3,  9,  2,  8, 11 } ,
  { 13, 11,  7, 14, 12,  1,  3,  9,  5,  0, 15,  4,  8,  6,  2, 10 } ,
  {  6, 15, 14,  9, 11,  3,  0,  8, 12,  2, 13,  7,  1,  4, 10,  5 } ,
  { 10,  2,  8,  4,  7,  6,  1,  5, 15, 11,  9, 14,  3, 12, 13 , 0 } ,
};

static void blake2s_set_lastnode( blake2s_state *S )
{
  S->f[1] = (uint32_t)-1;
}

/* Some helper functions, not necessarily useful */
static int blake2s_is_lastblock( const blake2s_state *S )
{
  return S->f[0] != 0;
}

static void blake2s_set_lastblock( blake2s_state *S )
{
  if( S->last_node ) blake2s_set_lastnode( S );

  S->f[0] = (uint32_t)-1;
}

static void blake2s_increment_counter( blake2s_state *S, const uint32_t inc )
{
  S->t[0] += inc;
  S->t[1] += ( S->t[0] < inc );
}

static void blake2s_init0( blake2s_state *S )
{
  size_t i;
  memset( S, 0, sizeof( blake2s_state ) );

  for( i = 0; i < 8; ++i ) S->h[i] = blake2s_IV[i];
}

/* init2 xors IV with input parameter block */
int blake2s_init_param( blake2s_state *S, const blake2s_param *P )
{
  const unsigned char *p = ( const unsigned char * )( P );
  size_t i;

  blake2s_init0( S );

  /* IV XOR ParamBlock */
  for( i = 0; i < 8; ++i )
    S->h[i] ^= load32( &p[i * 4] );

  S->outlen = P->digest_length;
  return 0;
}


/* Sequential blake2s initialization */
int blake2s_init( blake2s_state *S, size_t outlen )
{
  blake2s_param P[1];

  /* Move interval verification here? */
  if ( ( !outlen ) || ( outlen > BLAKE2S_OUTBYTES ) ) return -1;

  P->digest_length = (uint8_t)outlen;
  P->key_length    = 0;
  P->fanout        = 1;
  P->depth         = 1;
  store32( &P->leaf_length, 0 );
  store32( &P->node_offset, 0 );
  store16( &P->xof_length, 0 );
  P->node_depth    = 0;
  P->inner_length  = 0;
  /* memset(P->reserved, 0, sizeof(P->reserved) ); */
  memset( P->salt,     0, sizeof( P->salt ) );
  memset( P->personal, 0, sizeof( P->personal ) );
  return blake2s_init_param( S, P );
}

int blake2s_init_key( blake2s_state *S, size_t outlen, const void *key, size_t keylen )
{
  blake2s_param P[1];

  if ( ( !outlen ) || ( outlen > BLAKE2S_OUTBYTES ) ) return -1;

  if ( !key || !keylen || keylen > BLAKE2S_KEYBYTES ) return -1;

  P->digest_length = (uint8_t)outlen;
  P->key_length    = (uint8_t)keylen;
  P->fanout        = 1;
  P->depth         = 1;
  store32( &P->leaf_length, 0 );
  store32( &P->node_offset, 0 );
  store16( &P->xof_length, 0 );
  P->node_depth    = 0;
  P->inner_length  = 0;
  /* memset(P->reserved, 0, sizeof(P->reserved) ); */
  memset( P->salt,     0, sizeof( P->salt ) );
  memset( P->personal, 0, sizeof( P->personal ) );

  if( blake2s_init_param( S, P ) < 0 ) return -1;

  {
    uint8_t block[BLAKE2S_BLOCKBYTES];
    memset( block, 0, BLAKE2S_BLOCKBYTES );
    memcpy( block, key, keylen );
    blake2s_update( S, block, BLAKE2S_BLOCKBYTES );
    secure_zero_memory( block, BLAKE2S_BLOCKBYTES ); /* Burn the key from stack */
  }
  return 0;
}

#define G(r,i,a,b,c,d)                      \
  do {                                      \
    a = a + b + m[blake2s_sigma[r][2*i+0]]; \
    d = rotr32(d ^ a, 16);                  \
    c = c + d;                              \
    b = rotr32(b ^ c, 12);                  \
    a = a + b + m[blake2s_sigma[r][2*i+1]]; \
    d = rotr32(d ^ a, 8);                   \
    c = c + d;                              \
    b = rotr32(b ^ c, 7);                   \
  } while(0)

#define ROUND(r)                    \
  do {                              \
    G(r,0,v[ 0],v[ 4],v[ 8],v[12]); \
    G(r,1,v[ 1],v[ 5],v[ 9],v[13]); \
    G(r,2,v[ 2],v[ 6],v[10],v[14]); \
    G(r,3,v[ 3],v[ 7],v[11],v[15]); \
    G(r,4,v[ 0],v[ 5],v[10],v[15]); \
    G(r,5,v[ 1],v[ 6],v[11],v[12]); \
    G(r,6,v[ 2],v[ 7],v[ 8],v[13]); \
    G(r,7,v[ 3],v[ 4],v[ 9],v[14]); \
  } while(0)

static void blake2s_compress( blake2s_state *S, const uint8_t in[BLAKE2S_BLOCKBYTES] )
{
  uint32_t m[16];
  uint32_t v[16];
  size_t i;

  for( i = 0; i < 16; ++i ) {
    m[i] = load32( in + i * sizeof( m[i] ) );
  }

  for( i = 0; i < 8; ++i ) {
    v[i] = S->h[i];
  }

  v[ 8] = blake2s_IV[0];
  v[ 9] = blake2s_IV[1];
  v[10] = blake2s_IV[2];
  v[11] = blake2s_IV[3];
  v[12] = S->t[0] ^ blake2s_IV[4];
  v[13] = S->t[1] ^ blake2s_IV[5];
  v[14] = S->f[0] ^ blake2s_IV[6];
  v[15] = S->f[1] ^ blake2s_IV[7];

  ROUND( 0 );
  ROUND( 1 );
  ROUND( 2 );
  ROUND( 3 );
  ROUND( 4 );
  ROUND( 5 );
  ROUND( 6 );
  ROUND( 7 );
  ROUND( 8 );
  ROUND( 9 );

  for( i = 0; i < 8; ++i ) {
    S->h[i] = S->h[i] ^ v[i] ^ v[i + 8];
  }
}

#undef G
#undef ROUND

int blake2s_update( blake2s_state *S, const void *pin, size_t inlen )
{
  const unsigned char * in = (const unsigned char *)pin;
  if( inlen > 0 )
  {
    size_t left = S->buflen;
    size_t fill = BLAKE2S_BLOCKBYTES - left;
    if( inlen > fill )
    {
      S->buflen = 0;
      memcpy( S->buf + left, in, fill ); /* Fill buffer */
      blake2s_increment_counter( S, BLAKE2S_BLOCKBYTES );
      blake2s_compress( S, S->buf ); /* Compress */
      in += fill; inlen -= fill;
      while(inlen > BLAKE2S_BLOCKBYTES) {
        blake2s_increment_counter(S, BLAKE2S_BLOCKBYTES);
        blake2s_compress( S, in );
        in += BLAKE2S_BLOCKBYTES;
        inlen -= BLAKE2S_BLOCKBYTES;
      }
    }
    memcpy( S->buf + S->buflen, in, inlen );
    S->buflen += inlen;
  }
  return 0;
}

int blake2s_final( blake2s_state *S, void *out, size_t outlen )
{
  uint8_t buffer[BLAKE2S_OUTBYTES] = {0};
  size_t i;

  if( out == NULL || outlen < S->outlen )
    return -1;

  if( blake2s_is_lastblock( S ) )
    return -1;

  blake2s_increment_counter( S, ( uint32_t )S->buflen );
  blake2s_set_lastblock( S );
  memset( S->buf + S->buflen, 0, BLAKE2S_BLOCKBYTES - S->buflen ); /* Padding */
  blake2s_compress( S, S->buf );

  for( i = 0; i < 8; ++i ) // Output full hash to temp buffer
    store32( buffer + sizeof( S->h[i] ) * i, S->h[i] );

  memcpy( out, buffer, outlen );
  //secure_zero_memory(buffer, sizeof(buffer));
  return 0;
}

int blake2s( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen )
{
  blake2s_state S[1];

  /* Verify parameters */
  if ( NULL == in && inlen > 0 ) return -1;

  if ( NULL == out ) return -1;

  if ( NULL == key && keylen > 0) return -1;

  if( !outlen || outlen > BLAKE2S_OUTBYTES ) return -1;

  if( keylen > BLAKE2S_KEYBYTES ) return -1;

  if( keylen > 0 )
  {
    if( blake2s_init_key( S, outlen, key, keylen ) < 0 ) return -1;
  }
  else
  {
    if( blake2s_init( S, outlen ) < 0 ) return -1;
  }

  blake2s_update( S, ( const uint8_t * )in, inlen );
  blake2s_final( S, out, outlen );
  return 0;
}